Quote Originally Posted by cowanw View Post
I wonder if this demonstates a difference between the subtractive system of using white light and the additive system of a Blue/Green system.
Otherwise I have a hard time understanding how using a 1 setting of this much green and this much blue (plus this much blue for the #5 exposure) is different from this much green and (this much blue plus this much blue for the #5 exposure). Moving the brackets does not change the total quantity of green and blue. Comments?
Cowanw, I believe there is no difference in the final result, whether you use 00 or 1, with a 4 or a 5, when split-printing, except for the inability to reach the extreme grade of 00 or 5 if those filters are not used. The difference, however, is in the seemingly illogical relationship of the midtones affected by the discontinuity in the emulsion overlap, and the remaining tones, when moving from grade 00 to 0 and onwards. To put it in other words, as you move up a grade, from 00 to 0, and then towards 1, some midtones will immediately print denser at 00, than they would at 0, before they resume their march towards increased density at higher grades. I think this is what leads to a "solarised" look, that Bob Carnie mentioned when describing his 00 experience, see post 43 of this LFPP thread. You can see this in the two jumps of the 00 and 0 grade curves, which I have, rather poorly, plotted belowódisregard my error of a non-speed matched system, which lead to the curves not intersecting, as they should, at 0.60 logD. Notice the overall shape, and those almost 1 f/stop jumps, of the 00 curve:

Ilford MGIV WT 500H Curves (not to be trusted).png

Quote Originally Posted by Steve Smith View Post
According to Ilford's data sheet, all of their emulsion layers are sensitive to blue with varying sensitivities to green added.
Thank you, Steve, for correcting me.